Stripping composition which can be used in particular in the construction and yachting field

ABSTRACT

The invention relates to a stripping composition which can be used in the construction field, especially for the stripping of external organic coatings, such as exterior waterproof coatings and thin films, and in the yachting field, for the stripping of antifouling coatings, characterized in that it comprises: 
     at least one dibasic ester, 
     at least one dipolar aprotic solvent, 
     at least one inorganic filler, 
     water, 
     at least one cellulose thickener, 
     at least one dispersing agent and activators.

The present invention relates to a stripping composition which can beused in particular in the construction field, especially for thestripping of external organic coatings, such as thick plastic coatings(TPC), exterior waterproof coatings and thin films, and in the yachtingfield, for the stripping of antifouling paints.

Exterior waterproof coatings, with a rubbery appearance, are impermeableto air, to oxygen and to water vapour and are based on acrylic orstyrene-acrylic polymers.

In the construction field, most paint strippers are based on methylenechloride with methanol added. They can be thickened with cellulosecompounds and can comprise an inorganic filler.

However, there is an increasing search to replace methylene chloridebecause of its very high volatility and very high noxiousness.Replacement products for the synergistic methylene chloride-methanolmixture exist but they are generally much more expensive and form atleast 90% by weight of the composition of the formulation. The remaining10% are composed of a thickener (generally chosen from cellulose oracrylic derivatives), itself generally even more expensive than thesolvents, and various additives: activator, surfactant or corrosioninhibitor.

In the yachting field, the stripping of the antifouling coating,composed of numerous paint layers (5 to 10), is carried out by sandingdown. This way of operating is lengthy and produces a great deal ofdust. In addition, the use of stripping formulas based on methylenechloride is prohibited as they attack the gelcoat, which is a leaktightcoating.

A subject-matter of the present invention is thus a strippingcomposition which can be used in particular in the construction field,especially for the stripping of exterior waterproof coatings, thickplastic coatings (TPC) and thin films, and in the yachting field, forthe stripping of antifouling paints, characterized in that it comprises:

(A) at least one dibasic ester,

(B) at least one dipolar aprotic solvent,

(C) at least one inorganic filler with a thickening nature,

(D) water,

(E) at least one activator,

(F) at least one dispersant, and

(G) at least one cellulose thickener.

The composition according to the invention can comprise, per 100 partsby weight of (A)+(B)+(C)+(D)+(E)+(F)+(G):

10 to 50, in particular 25 to 45, parts by weight of (A);

10 to 30, in particular 15 to 25, parts by weight of (B);

20 to 40, in particular 25 to 35, parts by weight of (C);

10 to 25, in particular 15 to 20, parts by weight of (D);

1 to 15, in particular 1 to 10, parts by weight of (E);

0.2 to 2, in particular 0.4 to 1.2, parts by weight of (F); and

0.2 to 1, in particular 0.3 to 0.6, part by weight of (G).

The dibasic ester or esters (A) are chosen in particular from aliphaticdibasic esters, in particular C₁-C₄ alkyl diesters of one or more C₄-C₆aliphatic dibasic acids. Mention may in particular be made of dimethylsuccinate, dimethyl glutarate, dimethyl adipate and their mixtures.

The dipolar aprotic solvents (B) are advantageously chosen from dimethylsulphoxide, N-methylpyrrolidone, propylene carbonate, dimethylformamide,acetonitrile, N-methylmorpholine, butyrolactone and dimethylacetamide.Dimethyl sulphoxide and N-methylpyrrolidone are preferred.

The term “inorganic filler with a thickening nature (C)” is understoodto mean a natural or synthetic inorganic powder which can result informulations for which the viscosity is of the order of 6 000 mPa·s at20 revolutions/min or 2 000 mPa·s at 100 revolutions/min.

The inorganic filler or fillers generally have a mean particle size ofbetween 0.1 and 200 μm, more particularly between 1 and 100 μm. A finerparticle size makes it possible to obtain the same viscosity while usingless filler, which is not economically desirable.

Mention may be made, as examples of inorganic fillers, of calciumcarbonate, silica, calcium phosphite, calcium hydroxide (Ca(OH)₂), clayor bentonite. Preferably, calcium phosphite will be used.

Mention will be made, as activators (E) which can be used according tothe present invention, of alkyl alkoxypropionates, such as ethyl3-ethoxypropionate (EEP), terpenes, such as D-limonene, or the mixtureof these compounds.

Use will preferably be made of ethyl 3-ethoxypropionate and/orD-limonene.

Mention may be made, as example of dispersing agent (F), of the acidicphosphoric ester of 2-ethylhexanol, sold by Ceca under the nameBeycostat A081.

Mention may be made, as example of cellulose thickener (G), of Methocell311, sold by Dow Chemical Co., the process for the preparation of whichis disclosed in U.S. Pat. No. 3,388,082, entitled “Hydroxypropyl methylcellulose ethers”.

The stripping composition of the invention has proved to be highlyadvantageous; this is because, after it has been applied and then leftto act for a few tens of minutes, it is sufficient to shift the drystrips using a paint knife. Wet and sticky waste, which is alwaysdifficult to remove and to treat, is avoided and most of the time aclean substrate, such as a concrete or brick wall, is obtained.

In addition, in the yachting field, the stripping composition does notattack the gelcoat layer, which is a leaktight coating generally ofpolyester.

The stripping composition according to the present invention alsoexhibits the advantage of being stable on storage.

The following examples illustrate the present invention. In theseexamples, the ingredients used are as follows:

Dibasic ester:

DBE=dibasic ester having the following composition (as % by weight):

dimethyl adipate/dimethyl glutarate/dimethyl succinate:

15/62/23, sold by Rhône-Poulenc under the name RPDE.

Polar aprotic solvent: DMSO

Activators used=D-limonene and ethyl

3-ethoxypropionate of formula C₂H₅O—CH₂CH₂CO₂C₂H₅, hereinafter denotedby EEP.

Cellulose thickener=cellulose thickener sold by Dow Chemical Co. underthe name Methocell 311.

Dispersing agent=acidic phosphoric ester of 2-ethylhexanol, sold underthe name Beycostat A81.

CaHPO₃=natural calcium phosphite, produced by Ceca.

All the preparations are carried out at ambient temperature (25° C.) andwith stirring (approximately 400 revolutions/min), preferably with aturbine which makes possible dispersion of solids in the liquids. Thesolvents (DMSO, DBE), the D-limonene, the water and the dispersant areintroduced first. Then the calcium phosphite and the cellulose thickenerare added.

In these examples, all the proportions cited are in parts by weight.

PREPARATION EXAMPLE 1

DMSO 12 DBE 35 D-Limonene 5 Water 17 Beycostat A81 0.5 Methocell 311 0.4Calcium phosphite 30

The flash point of the formula is 62° C.

PREPARATION EXAMPLE 2

DMSO 10.2 DBE 29.6 D-Limonene 4.2 EEP 8 Water 17 Beycostat A81 0.7Methocell 311 0.5 Calcium phosphite 30

The flash point of the formula is 64° C.

PREPARATION EXAMPLE 3

DMSO 12 DBE 35.1 EEP 5 Water 17 Beycostat A81 0.4 Methocell 311 0.4Calcium phosphite 30

PREPARATION EXAMPLE 4 Not in Accordance with the Invention

DMSO 12.77 DBE 37.23 D-Limonene 5.32 Beycostat A81 1.06 Methocell 3110.21 Calcium phosphite 50

After having produced the three preparations described above and havingleft them to stand for two days, it is found that Preparation 4 has setsolid, whereas Preparations 1, 2 and 3 have remained flowing.

Preparation 4 thus has to be stirred in order to be able to be decantedor to be deposited. Preparations 1, 2 and 3 can be decanted or can bedeposited without any preliminary stirring.

APPLICATIONAL EXAMPLE 1

This applicational example relates to the construction stripping of anexterior coating such as TPC (thick plastic coating). More specifically,it relates to the stripping of an acrylic roughcast with a thickness ofapproximately 2 mm deposited on brick.

After depositing Preparations 1, 2, 3 and 4 in a thick layer (thicknessof 0.5 to 1 mm) and waiting for the necessary time, the coating isscraped off with a knife, resulting in the formation of dry strips.

On this type of coating, the time of action has to be 6 h forPreparation 4, 5 h for Preparation 1 and 4 h for Preparations 2 and 3.

APPLICATIONAL EXAMPLE 2

This applicational example relates to the construction stripping of anexterior coating such as an exterior waterproofing agent known asParadox (Plasdox) deposited in 2 layers on brick.

On this coating, the formulas 1, 2 and 3 result in stripping afterapproximately 1 to 2 h, giving strips by scraping with a knife.

The formulas 2 and 3 seem to give better results, leaving the substratebare.

APPLICATIONAL EXAMPLE 3

This applicational example relates to the use of the formulas 1, 2 or 3for the stripping of an antifouling coating from a 9-meter boat.

The stripping was carried out during the day.

In connection with certain components of the composition, it is to beunderstood that the “activator” accelerates kinetics of the stripping,and the “dispersant” results in a stable dispersion of the inorganicfiller in the stripping composition.

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples. Also, the preceding specific embodiments are to be construedas merely illustrative, and not limitative of the remainder of thedisclosure in any way whatsoever.

The entire disclosure of all applications, patents and publications,cited above and below, and of corresponding French application00/06.755, are hereby incorporated by reference.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

What is claimed is:
 1. A stripping composition, comprising per 100 partsof (A)+(B)+(C)+(D)+(E)+(F) and (G): (A) 10 to 50 parts by weight of atleast one dibasic ester, (B) 10 to 30 parts by weight of at least onedipolar aprotic solvent, (C) 20 to 40 parts by weight of at least oneinorganic filler with a thickening nature, (D) 10 to 25 parts by weightof water, (E) 1 to 15 parts by weight of at least one activator, (F) 0.2to 2 parts by weight of at least one dispersant, and (G) 0.2 to 1 partby weight of at least one cellulose thickener.
 2. A strippingcomposition according to claim 1, wherein comprising, per 100 parts byweight of (A)+(B)+(C)+(D)+(E)+(F)+(G): 25 to 45 parts by weight of (A),15 to 25 parts by weight of (B), 25 to 35 parts by weight of (C), 15 to20 parts by weight of (D), 1 to 10 parts by weight of (E), 0.4 to 1.2parts by weight of (F), and 0.3 to 0.6 parts by weight of (G).
 3. Astripping composition according to claim 2, wherein: (A) comprises atleast one of dimethyl adipate, dimethyl glutarate, and dimethylsuccinate, (B) comprises dimethyl sulfoxide, (C) comprises Ca HPO₃, (D)is water, (E) comprise at least one of D-limonene and ethyl 3-ethoxypropionate, (F) comprise an acidic phosphine ester of 2-ethyl hexanol,and (G) methyl cellulose.
 4. A stripping composition according to claim1, wherein the dibasic esters (A) are aliphatic dibasic esters.
 5. Astripping composition according to claim 1, wherein the dibasic ester oresters (A) comprises dimethyl succinate, dimethyl glutarate, dimethyladipate or mixtures thereof.
 6. A stripping composition according toclaim 1, wherein the dipolar aprotic solvent or solvents (B) comprise(s)dimethyl sulphoxide, N-methypyrrolidone, propylene carbonate,dimethylformamide, acetonitrile, N-methylmorpholine, butyrolactone anddimethylacetamide or mixtures thereof.
 7. A stripping compositionaccording to claim 5, wherein the dipolar aprotic solvent or solvents(B) comprise(s) dimethyl sulphoxide, N-methypyrrolidone, propylenecarbonate, dimethylformamide, acetonitrile, N-methylmorpholine,butyrolactone and dimethylacetamide or mixtures thereof.
 8. A strippingcomposition according to claim 1, wherein the inorganic filler (C)comprises calcium phosphite.
 9. A stripping composition according toclaim 5, wherein the inorganic filler (C) comprises calcium phosphite.10. A stripping composition according to claim 6, wherein the inorganicfiller (C) comprises calcium phosphite.
 11. A stripping compositionaccording to claim 7, wherein the inorganic filler (C) comprises calciumphosphite.
 12. A stripping composition according to claim 1, whereinactivator (E) comprises ethyl 3-ethoxypropionate and/or D-limonene. 13.A stripping composition according to claim 5, wherein activator (E)comprises at least one of ethyl 3-ethoxypropionate and D-limonene.
 14. Astripping composition according to claim 6, wherein activator (E)comprises at least one of ethyl 3-ethoxypropionate and D-limonene.
 15. Astripping composition according to claim 7, wherein activator (E)comprises at least one of ethyl 3-ethoxypropionate and D-limonene.
 16. Astripping composition according to claim 8, wherein activator (E)comprises at least one of ethyl 3-ethoxypropionate and D-limonene.
 17. Astripping composition according to claim 9, wherein activator (E)comprises at least one of ethyl 3-ethoxypropionate and D-limonene.
 18. Astripping composition according to claim 10, wherein activator (E)comprises at least one of ethyl 3-ethoxypropionate and D-limonene.
 19. Astripping composition according to claim 11, wherein activator (E)comprises at least one ethyl 3-ethoxypropionate and D-limonene.
 20. Astripping composition according to claim 1, wherein the dispersant (F)comprises an acidic phosphoric ester of 2-ethylhexanol.
 21. A strippingcomposition according to claim 19, wherein the dispersant (F) comprisesan acidic phosphoric ester of 2-ethylhexanol.
 22. A method of strippingan external organic coating from a substrate, said method comprisingapplying a composition according to claim 1 to said external organiccoating and thereafter removing the external organic coating from thesubstrate.
 23. A method according to claim 21, wherein the externalorganic coating comprises an exterior waterproof coating, a thickplastic coating or a thin film.
 24. A method according to claim 21,wherein the exterior organic coating comprises an antifouling coatingand the substrate comprises a surface of a boat.